Erythema refers to redness, or inflammation of vascularized areas of the body, which can increase as a result of various causes including diseases and disorders of the mucosa and skin, and of the dental pulp (“tooth nerve”) tissue. There is a long-standing problem of determining the health status of the contents of the dental pulp chamber within teeth. The pulp consists of different tissues, including a dense network of small blood vessels. In the healthy state, the pulp tissue is red in color due to a rich blood supply. When a tooth becomes diseased from caries (decay), or injured from trauma, the dental pulp becomes inflamed, and in the case of caries, the degree of erythema might increase, first near the area of disease (caries) in the crown portion of the tooth, and ultimately progressing throughout the pulp chamber and root canal(s) to the apex of the tooth, where the pulp tissue joins the systemic circulation in the surrounding alveolar bone. This increased erythema eventually disappears as the pulp becomes overwhelmed by the inflammatory process, loses its blood supply, and becomes necrotic. This can be painful, but in many cases it is a silent process. The resulting infection can ultimately spread to the soft tissues of the face, involving vital structures of the head and neck, and on rare occasions can result in death.
Methods to determine the health status of the dental pulp are crude, often highly subjective, and have not progressed significantly in the last three decades. Part of the problem stems from the two different layers of calcified tissue, dentin and enamel, that surround the pulp tissue. The standard method for visualizing the dental pulp is to use the intraoral dental radiograph, which only gives a two-dimensional view, or shadow, of the pulp chamber. Radiographs do not allow for differentiation between the extremes of entirely healthy versus completely necrotic pulp tissue.
The determination of the degree of erythema, and therefore the degree of disease of pulp tissue, has always been of interest to dentists in clinical practice and in research, as it would allow for early diagnosis, less invasive treatment, and less costly treatment. It would also allow for the development of medications to prevent or treat pulpal inflammation. This would provide for early intervention in situations where the inflammatory process could be altered, and provide a research tool for studies concerning disorders where tooth vascularity may be altered by changes in the blood supply. There are no practical or commercial methods for quantifying erythema within teeth, and existing methods of determining the health status of the pulp are highly subjective, poorly reproducible, and often do not detect disease at an early stage when treatment and preventative strategies are most effective.